Test-retest studies for assessing stability and change are widely used in different domains and allow improved or additional individual estimates of interest to be obtained. However, if these estimates are to be validly interpreted the responses given at Time-2 must be free of retest effects, and the fulfilment of this assumption must be…

This article proposes a model-based procedure, intended for personality measures, for exploiting the auxiliary information provided by the certainty with which individuals answer every item (response certainty). This information is used to (a) obtain more accurate estimates of individual trait levels, and (b) provide a more detailed assessment of…

Describes an item response theory-based structural equation model that allows the short-term stability and the magnitude of retest effects to be assessed for some types of personality traits. Provides an empirical application of the model and discusses the substantive implications of the results. (SLD)

This article discusses the rationale of an item response theory (IRT) model, based on Thurstone scaling, for personality measurement and suggests procedures for (a) estimating the location and slope parameters of the person response curve (PRC), (b) assessing the precision of the estimates, and (c) assessing the model-data fit. The relations…

Developed an item response theory model of response stability based on the local independence principle. Tested the model, which predicts response changes under repeated administrations of the same instrument, with real data for 432 Spanish undergraduates. Results indicate that the model predictions are approximately fulfilled. (SLD)